Question: William ate 3 slices of pie. Luis ate 5 slices. If William ate $\dfrac{3}{12}$ of the pie, what fraction of the pie is remaining?
Solution: If 3 slices represent $\dfrac{3}{12}$ of the pie, there must have been a total of 12 slices. $\text{fraction of pie remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 8 slices, which leaves 4 out of 12 slices remaining. There is $\dfrac{4}{12}$ of the pie remaining.